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Flight effects on noise by the JT8D engine with inverted primary/fan flow as measured in the NASA-Ames 40 by 80 foot wind tunnelA JT8D-17R engine with inverted primary and fan flows was tested under static conditions as well as in the NASA Ames 40 by 80 Foot Wind Tunnel to determine static and flight noise characteristics, and flow profile of a large scale engine. Test and analysis techniques developed by a previous model and JT8D engine test program were used to determine the in-flight noise. The engine with inverted flow was tested with a conical nozzle and with a plug nozzle, 20 lobe nozzle, and an acoustic shield. Wind tunnel results show that forward velocity causes significant reduction in peak PNL suppression relative to uninverted flow. The loss of EPNL suppression is relatively modest. The in-flight peak PNL suppression of the inverter with conical nozzle was 2.5 PNdb relative to a static value of 5.5 PNdb. The corresponding EPNL suppression was 4.0 EPNdb for flight and 5.0 EPNdb for static operation. The highest in-flight EPNL suppression was 7.5 EPNdb obtained by the inverter with 20 lobe nozzle and acoustic shield. When compared with the JT8D engine with internal mixer, the inverted flow configuration provides more EPNL suppression under both static and flight conditions.
Document ID
19780018206
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Strout, F. G. (Boeing Commercial Airplane Co. Seattle, WA, United States)
Date Acquired
September 3, 2013
Publication Date
June 1, 1978
Subject Category
Aircraft Propulsion And Power
Report/Patent Number
NASA-CR-2996
Accession Number
78N26149
Funding Number(s)
CONTRACT_GRANT: NAS2-9302
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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